The present invention relates to a Venetian blind, and more particularly to a Venetian blind having a tilt means with improved ladder strings, so that upper slats of the blind could be lowered to a distance below a head rail of the blind and a light transmissible area without being shielded by any slat is provided above the blind, and the lowered slats could still be deployed and tilted to adjust volume and direction of light projected through the blind.
A Venetian blind is widely welcomed because it has the functions of blocking sunrays, adjusting indoor brightness, decorating rooms, etc. As can be seen from FIG. 1, a conventional Venetian blind mainly includes a head rail 10, a bottom rail 20, a plurality of slats 30, a lift means 40 including multiple lift cords 41, and a tilt means 50 including multiple ladder strings 51. Typically, the lift cords 41 are laterally symmetrically provided on the blind to balance the bottom rail 20 and the slats 30 of the blind for them to be lowered or lifted synchronously. The number of ladder strings 51 depends on an overall width of the slats 30. The head rail 10 is fixedly attached to an upper edge 61 of a window 60. By pulling the lift cords 41, the bottom rail 20 and the slats 30 may be horizontally lifted or lowered relative to the head rail 10 as desired. For example, the slats 30 may be fully lowered to locate the bottom rail 20 immediately above a stool 62 of the window 60. At this point, all the slats 30 of the blind are deployed to shield entire area of the window 60, as shown in FIG. 2. Alternatively, the slats 30 may be partially lowered to locate the bottom rail 20 at any desired height above the stool 62 of the window 60. At this point, slats 30a at an upper part of the slats 30 are deployed while slats 30b at a lower part of the slats 30 are stacked on the bottom rail 20, as shown in FIG. 3. In either case of FIG. 2 or 30a in FIG. 3, the deployed slats 30a could be tilted upward or downward within 180 degrees through operation of the tilt means 50 to adjust the ladder strings 51. By tilting the above-mentioned slats to different angle of inclination, amount and direction of light projected into a room via the Venetian blind can be controlled and adjusted.
There may be many changes in the manner of operating the tilt means 50 and in the design of elements included in the tilt means 50. However, most of the tilt means 50 have similar operating principle. To be more specific, a front and a rear vertical strings 51a, 51b of each ladder string 51 are fixedly connected at their respective upper ends to a top center of a tilter, such that the front and the rear vertical strings 51a, 51b are separately located at front and rear sides of the tilter to face each other. The tilter is a lever-shaped rotatable member having two opposite arms. All the tilters are fixedly mounted on and horizontally spaced along the same one rotary shaft. The arms of the tilters have the same length and extend by a predetermined distance. By turning a tilt control bar 52 of the tilt means 50 clockwise or counterclockwise, or manipulating the tilt control bar 52 in other manner, the rotary shaft could be turned in two opposite directions by 90 degrees each, bringing the tilter to rotate along with the rotary shaft from a horizontal position to a vertical position. At this point, the front and the rear vertical strings 51a, 51b of the ladder strings 51 are ascended and descended, respectively, relative to each other, causing multiple spaced transverse ladders 51c of the ladder strings 51 extended between the front and the rear strings 51a, 51b, as well as slats 30a, 30b associated with the horizontal ladders 51c, to tilt by a desired angle. To lift the lowered bottom rail 20 and the previously deployed slats 30a, 30b to locate them immediately below the head rail 10, simply operate the lift means 40 and the tilt means 50 backward.
The lift means 40 and the tilt means 50, either manually or electrically operated, both have various types of designs available in the market. However, all these currently available lift means 40 and tilt means 50 for the conventional Venetian blind can only allow the bottom rail 20 and slats 30a, 30b of the slats 30 to be horizontally lowered to a desired height relative to the stool 62 of the window 60 and be lifted toward the head rail 10. That is, when the slats 30 is partially lowered, an area of the window 60 that is not shielded by any slat and is therefore completely light transmissible is always located below the bottom rail 20 and above the stool 62. However, in many cases, people usually need the blind to shield only a lower part or a middle part of a window and leave the remaining upper part of the window in a light transmissible state. It is obvious the conventional Venetian blind could not satisfy this requirement.
U.S. Pat. No. 5,443,108 entitled xe2x80x9cUpwardly Deployed Privacy Blindxe2x80x9d discloses a Venetian blind in which slats are stacked above the stool of the window when the blind is not in use or is partially lifted to provide a slat-free and light-transmissible area above the blind. This type of Venetian blind includes a fixed head rail, a fixed bottom rail, and an up and down movable middle rail, and therefore has more complicated structure. Moreover, the design of stacking slats at a lower part of the blind does not meet most people""s practice of lifting and stacking the slats to an upper part of the blind when the blind is not in use.
There is a commercially available top-down pleated shade that includes a fixed head rail attached to the upper edge of the window, and a movable head rail connected to an upper edge of a pleated shade body. Through manipulation of operating elements inside the fixed head rail, the movable head rail and the pleated shade body may be lowered to separate from the fixed head rail, so that an area of the window below the fixed head rail and above the pleated shade body is not shield by the shade body and is therefore light transmissible. However, the movable head rail would extend across the window and forms a visual barrier when the pleated shade is lowered. The main difference between the top-down pleated blind and the top-down Venetian Blind is that the former needs only to lower the fablic away from the top head rail while the latter owns further function of tilting the slats in different angles.
It is therefore desirable to develop a top-down Venetian blind that overcomes the drawbacks existing in the conventional Venetian blinds and the pleated shade.
A primary object of the present invention is to provide a top-down Venetian blind that after the Venetian blind is fully or partly dropped, the upper portion of the slats could be lowered to a distance below the head rail of the blind and a light-transmissible area without being shielded by any slat is provided. A ladder string includes a front and a rear vertical strings connected with a plurality of horizontal ladders. Two extending cords of suitable length without horizontal ladders are connected to the tops of the front and the rear vertical strings of the ladder strings and pass through the tilting means and then wound around a reel mounted on a rotary shaft in the head-rail. The extended cords are synchronously released from the reel when the rotary shaft is turned forward, so that upper portion of slats are lowered to a distance below the head rail and a light transmissible area without being shielded by any slat is provided when the rotary shaft is turned backward the extended cords will be rewound around the reel and the upper portion of slats is lifted to the top of the blind.
Another object of the present invention is to provide a top-down Venetian blind in which the slats located below the light transmissible area but not stacked on the bottom rail would still be deployed and tilted to adjust volume and direction of light projected through the blind.
A further object of the present invention is to provide a top-down Venetian blind in which the tilter each includes two opposite lever arms provided with an end hole each. The upper ends of the hanging sections of the ladder string are separately upward extended through the end holes, turned to pass below a central shaft of the tilter, and then turned upward to connect to and wind around the reel. Whereby the hanging sections could be freely released from or rewound around the reel via the tilter without affecting tilting of the slats through the tilter and the ladder strings.